Extracting inline CSS from HTML Purifier
    voodoofied: Assigning semantics to elements

Sander Tekelenburg brought to my attention the poor programming style of
inline CSS in HTML documents.  In an ideal world, we wouldn't be using inline
CSS at all: everything would be assigned using semantic class attributes
from an external stylesheet.

With ExtractStyleBlocks and CSSTidy, this is now possible (when allowed, users
can specify a style element which gets extracted from the user-submitted HTML, which
the application can place in the head of the HTML document).  But there still
is the issue of inline CSS that refuses to go away.

The basic idea behind this feature is assign every element a unique identifier,
and then move all of the CSS data to a style-sheet. This HTML:

<div style="text-align:center">Big <span style="color:red;">things</span>!</div>

into

<div id="hp-12345">Big <span id="hp-12346">things</span>!</div>

and a stylesheet that is:

#hp-12345 {text-align:center;}
#hp-12346 {color:red;}

Beyond that, HTML Purifier can magically merge common CSS values together,
and a whole manner of other heuristic things.  HTML Purifier should also
make it easy for an admin to re-style the HTML semantically. Speed is not
an issue. Also, better WYSIWYG editors are needed.